Input buttons of a keypad of a conventional mobile phone and a character input device are marked with English characters and Arabic numerals thereon. For example, as shown in FIG. 1 illustrating a keypad, the keypad is configured so that a group of QZ(1), ABC(2), DEF(3), GHI(4), JKL(5), MNO(6), PRS(7), TUV(8) and WXY(9) can be allocated to input buttons thereof, respectively, or a group of ABC(2), DEF(3), GHI(4), JKL(5), MNO(6), PRS(7), TUV(8) and WXYZ(9) can be allocated to input buttons, respectively. Here, the numerals in the parentheses indicate a series of buttons which are allocated together with corresponding characters. Although the keypad is implemented so that each input button has English characters and numerals, the input button can be modified to allocate characters depending on the language of a corresponding nation or to allocate the characters together with English characters as occasion demands.
A conventional method of changing an input mode using a menu button is very inconvenient. When a user operates a menu button in a default input mode, various input modes are displayed on the screen, the user selects an input mode of the input modes using a direction key and an enter key. Whenever the users want to change an input mode, he or she should use the menu button repeatedly. Furthermore, whenever the user wants to return to the default input mode, the user should use the menu button repeatedly.
Also, since the punctuation marks, which are used to compose sentences, are included in a set of special characters, the character input mode must be frequently changed to the special character input mode using the menu button to input frequently used punctuation marks therein.
In the special characters input mode, a lot of special characters, such as $, {, @, =, <, &, ?, !, #, *, (, −, +, ^, %, and so on, can be inputted. These special characters include punctuation marks, which are frequently used to compose sentences, for example, a period (.), a question mark (?), a comma (,), a slash (/), and quotation marks (“, ”), a colon (:), a dash (-), a grave ({grave over ( )}), a less than sign (<), and so on. However, the conventional character input method has disadvantages in that the character input mode must be changed using the menu button to an input mode, in which the punctuation marks and the special characters are marked together marked.